mpl-animator 0.1.5

Turn any static matplotlib script into an animated GIF or MP4 by sweeping one or more variables

mpl-animator

Turn any static matplotlib script into an animated GIF or MP4 by sweeping a variable - no rewriting required.

Features

• Zero boilerplate - point it at an existing script, it figures out the rest
• Multi-variable animation - sweep multiple variables simultaneously with --var azim spin elev --range "0,360" "0,6.28" "20,40"; all variables share the same frame clock, each advances independently
• AST-based dependency tracking - automatically identifies which variables and calculations need to update each frame, across all animated variables
• Parallel rendering - renders frames across all CPU cores via multiprocessing, falls back to sequential automatically
• GIF and MP4 output - export as animated GIF (Pillow) or MP4 (ffmpeg); just add --format mp4
• Loop control - --loop 0 (forever, default), --loop 1 (play once), --loop N
• Ping-pong - --ping-pong plays forward then reversed for seamless looping GIFs
• Reverse - --reverse sweeps each range end → start
• Axis rotation - animate azim with ax.view_init to rotate 3D plots; animate angle with ax.set_theta_offset to spin polar plots
• Math expressions in ranges - --range "0,2*pi" just works
• 2D, 3D, and polar plots - handles plot_surface, scatter3D, subplots, polar axes, and more
• Single-file, standalone - mpl_animator.py can be dropped into any project with no install required; only depends on matplotlib, numpy, and Pillow (no exotic dependencies)
• Library API - importable as a Python module for use in notebooks or pipelines

Install

pip install mpl-animator

Or just copy the file - no install needed:

# copy mpl_animator.py into your project, then use it directly
python mpl_animator.py my_plot.py --var t --range "0,1"

Usage

If installed via pip, use the mpl-animator command. If using the file directly, replace mpl-animator with python mpl_animator.py - everything else is identical.

# Basic: animate variable `f` from 3 to 60 (outputs GIF by default)
mpl-animator wave_static.py --var f --range "3,60"

# Export as MP4 instead of GIF (requires ffmpeg)
mpl-animator plot.py --var t --range "0,2*pi" --format mp4

# Math expressions in range, custom frame count and FPS
mpl-animator plot.py --var t --range "0,2*pi" --frames 60 --fps 30

# Rotate a 3D plot by animating the camera azimuth
mpl-animator my_3d_plot.py --var azim --range "0,360" --frames 72 --fps 20

# Multi-variable: camera orbits (azim) while the object spins (spin) and camera rises (elev)
mpl-animator orbit_static.py --var azim spin elev --range "0,360" "0,6.28" "20,40" --frames 90 --fps 25 --ping-pong

# Ping-pong loop (plays forward then reversed — great for seamless GIFs)
mpl-animator plot.py --var t --range "0,1" --frames 60 --ping-pong

# Control output quality and parallelism
mpl-animator plot.py --var alpha --range "0,1" --dpi 150 --workers 8

# Custom output filename
mpl-animator plot.py --var t --range "0,1" --out my_animation.gif

This generates a <script>_animated.py file. Run it to produce the output:

python wave_static_animated.py              # parallel (default)
python wave_static_animated.py --sequential # single-threaded fallback

Examples

Example 1 - Wave & spectrum (2D)

wave_static.py plots a signal and its frequency spectrum for a fixed frequency f:

# wave_static.py  (key lines)
f   = 10.0                          # <- variable to animate
t   = np.linspace(0, 1, 1000)
y   = np.sin(2*np.pi*f*t) + 0.4*np.sin(2*np.pi*2*f*t)

freqs    = np.fft.rfftfreq(len(t), d=t[1]-t[0])
spectrum = np.abs(np.fft.rfft(y))

fig, (ax1, ax2) = plt.subplots(2, 1, figsize=(9, 6))
ax1.plot(t, y, 'royalblue', lw=1.5)
ax2.plot(freqs, spectrum, 'tomato', lw=1.5)
plt.show()

Animate f from 3 Hz to 60 Hz:

python mpl_animator.py examples/wave_static.py --var f --range "3,60" --frames 60 --fps 20
python wave_static_animated.py

The animator detects that y, spectrum depend on f, moves them into the per-frame update(), and keeps the figure/axes creation static - so only the data redraws each frame.

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Example 2 - 3D Lissajous curve

lissajous_3d_static.py draws a 3D Lissajous figure for fixed frequency ratio a:

# lissajous_3d_static.py  (key lines)
a  = 3.0          # <- variable to animate
b  = 2.0
c  = 1.0

t = np.linspace(0, 2 * np.pi, 1000)
x = np.sin(a * t + delta)
y = np.sin(b * t)
z = np.sin(c * t)

fig = plt.figure(figsize=(8, 6))
ax  = fig.add_subplot(111, projection='3d')
ax.scatter(x, y, z, c=colors, s=2, alpha=0.8)
ax.set_title(f"3D Lissajous  a={a:.1f}, b={b:.1f}, c={c:.1f}")
plt.show()

Animate a from 1 to 6, sweeping through different curve topologies:

python mpl_animator.py examples/lissajous_3d_static.py --var a --range "1,6" --frames 80 --fps 20
python lissajous_3d_static_animated.py

For 3D plots the animator calls fig.clear() and recreates the axes each frame (required to preserve the projection='3d' state), then re-runs all drawing commands with the new value of a.

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Example 3 - Cinematic 3D orbit (multi-variable)

orbit_static.py draws a torus knot for fixed camera position and object rotation:

# orbit_static.py  (key lines)
azim = 45.0          # camera azimuth in degrees      <- animated
spin = 0.0           # object self-rotation (radians) <- animated
elev = 20.0          # camera elevation in degrees    <- animated

# Object geometry: rotate the knot around its own Z axis
cx_rot = cx * np.cos(spin) - cy * np.sin(spin)
cy_rot = cx * np.sin(spin) + cy * np.cos(spin)

fig = plt.figure(figsize=(7, 7))
ax  = fig.add_subplot(111, projection='3d')
ax.plot_surface(xs, ys, zs, cmap='plasma', alpha=0.92)
ax.view_init(elev=elev, azim=azim)   # <- camera controlled by both azim and elev
plt.show()

All three variables sweep simultaneously from the same frame clock — the camera orbits a full 360°, the object spins one full turn, and the camera gently cranes upward. --ping-pong plays the sequence forward then reversed for a seamless loop:

python mpl_animator.py examples/orbit_static.py \
    --var azim spin elev \
    --range "0,360" "0,6.28318" "20,40" \
    --frames 90 --fps 25 --dpi 120 --ping-pong
python orbit_static_animated.py --sequential

The animator identifies that cx_rot, cy_rot, and the tube surface xs/ys/zs all depend on spin, and that ax.view_init depends on azim and elev — all three dependency chains are tracked and placed in update() automatically.

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How it works

1. Parses your script's AST to find which variables depend on the animated one
2. Splits code into static (run once) and dynamic (recalculated per frame)
3. Generates a new script with FuncAnimation (sequential 2D GIF), PNG+stitch (sequential MP4 or 3D), and multiprocessing (parallel) renderers

Library usage

from mpl_animator import animate

src = open("my_plot.py").read()

# Single variable
animated_code = animate(src, var="t", range_str="0,6.28", frames=60, fps=25)
open("my_plot_animated.py", "w").write(animated_code)

# Multiple variables — pass lists of equal length
animated_code = animate(
    src,
    var=["azim", "spin", "elev"],
    range_str=["0,360", "0,6.28", "20,40"],
    frames=90, fps=25, ping_pong=True,
)

# Export as MP4
animated_code = animate(src, var="t", range_str="0,6.28", fmt="mp4")

# Ping-pong loop (seamless forward+reverse)
animated_code = animate(src, var="t", range_str="0,1", ping_pong=True, loop=0)

Supported plot types

2D (plot, scatter, bar, hist, contour, imshow, ...), 3D (plot_surface, scatter3D, ...), polar, and anything else matplotlib draws.

Tests

pytest tests/ -v              # fast tests
pytest tests/ -v -m slow      # slow tests that generate actual GIFs/MP4s

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Author: Basem Rajjoub

Built with the assistance of Claude Code